A 7 m bar is pivoted at 2 m from the left end. A force of 60 N is applied downward on the left end and a force of 20 N is applied downward on the right end. What are the clockwise and counter-clockwise moments, and which direction would the bar rotate?

A 7 m bar is pivoted at 2 m from the left end. A force of 60 N is applied downward on the left end and a force of 20 N is applied downward on the right end. What are the clockwise and counter-clockwise moments, and which direction would the bar rotate?

• A. 80 Nm counter-clockwise, 100 Nm clockwise, counter-clockwise rotation
• B. 60 Nm counter-clockwise, 100 Nm clockwise, clockwise rotation
• C. 120 Nm counter-clockwise, 100 Nm clockwise, counter-clockwise rotation
• D. 120 Nm counter-clockwise, 100 Nm clockwise, clockwise rotation

Answer: (C)

To determine the moments and the direction of rotation for the 7 m bar, we first need to calculate the moments produced by the forces acting on either end of the bar about the pivot point. The bar is pivoted 2 m from the left end, meaning that the left section of the bar (where the 60 N force is applied) is 2 m from the pivot, while the right side (where the 20 N force is applied) extends 5 m from the pivot point to the right end of the bar. To calculate the clockwise and counter-clockwise moments: 1. **Clockwise Moment**: This is created by the 20 N force applied at the right end of the bar. The distance from the pivot to the point of force application is 5 m. The formula for the moment is: \[ \text{Moment} = \text{Force} \times \text{Distance} \] Plugging in the values: \[ \text{Clockwise Moment} = 20 \, \text{N} \times 5 \, \text{m} = 100 \, \text{Nm} \] 2. **Counter-clockwise

To determine the moments and the direction of rotation for the 7 m bar, we first need to calculate the moments produced by the forces acting on either end of the bar about the pivot point.

The bar is pivoted 2 m from the left end, meaning that the left section of the bar (where the 60 N force is applied) is 2 m from the pivot, while the right side (where the 20 N force is applied) extends 5 m from the pivot point to the right end of the bar.

To calculate the clockwise and counter-clockwise moments:

1. Clockwise Moment: This is created by the 20 N force applied at the right end of the bar. The distance from the pivot to the point of force application is 5 m. The formula for the moment is:

[

\text{Moment} = \text{Force} \times \text{Distance}

]

Plugging in the values:

[

\text{Clockwise Moment} = 20 , \text{N} \times 5 , \text{m} = 100 , \text{Nm}

]

2. **Counter-clockwise